The use of rigid fibrous glass ducts to supply and return air for residential and commercial heating, ventilating, and air conditioning systems is well known. The popularity of such duct systems has increased significantly during the past 25 years with millions of feet of fibrous glass duct work presently in operation in schools, shopping centers, office buildings, apartments, and residences throughout the United States. When compared to a traditional metal duct system, the use of a fibrous glass duct system can improve the overall quality of the indoor environment through its efficient thermal and acoustical properties, and its ability to virtually eliminate condensation problems. Moreover, a fiber glass duct system is generally less expensive to install than an insulated and sealed wrapped or lined sheet metal system because of faster and easier fabrication and installation. Fiber glass duct systems are also less weight and therefore easier to handle as compared to sheet metal systems.
Rigid fibrous glass ducts are fabricated from sheets of resin bonded inorganic glass fibers. Typically, one major surface of the sheet (hereinafter called duct board) includes a facing which serves as a finish and an air barrier/vapor retarder. The facing is typically a metal foil or a reinforced foil laminate. This faced surface ultimately serves as the outside surface of the assembled duct system.
Frequently, the other major surface of the duct board is coated or faced with a material to improve resistance to fabrication and job site installation damage and to provide the airstream surface of the assembled duct system with an abrasion resistant surface which may be cleaned with commonly available duct cleaning equipment. Duct board can vary in thickness, but is commonly supplied in 1 inch and 11/2 inch configurations.
The duct boards are fabricated by folding into square, rectangular, or multi-sided duct sections for use in both residential and commercial heating, ventilating, and air conditioning duct systems. The board is grooved at the fold lines and formed into duct sections, which are then stapled and sealed at the longitudinal joint. Sections are joined in the same way. Frequently, the duct boards are supplied with factory molded male and female shiplap edges to ensure tight and strong fabricated joints. In one commercially available configuration, the outside reinforced foil laminate air barrier extends over the full width of the male shiplap edges to serve as a sealing or stapling flap during fabrication. Duct boards are also commercially available without the shiplap edges in a butt edge configuration. Sealing of seams and joints is accomplished through the use of appropriate tapes. Such tapes include pressure-sensitive aluminum foil tapes, heat-activated aluminum foil/scrim tapes, and mastic and glass fabric tape systems.
Duct systems are frequently suspended from ceiling joists or rafters. Hangers and supports for the duct work are generally fabricated from metal channels, straps, rods and/or wires.
While the use of fibrous glass duct boards to form duct systems has resulted in significant improvements in the fabrication, installation and performance of residential and commercial air handling systems, further improvement would be beneficial. For instance, it would be beneficial if there were a device which would facilitate and improve the method of joining adjacent sections of duct work and result in stronger joints. It would also be beneficial if such a device could provide positive mechanical securement beyond that which is provided by the practice of taping to secure adjacent sections of duct work in place. Moreover, it would be beneficial if such a device could also be used to facilitate the hanging of the duct system.